LXR linux/arch/microblaze/mm/highmem.c

   1/*
   2 * highmem.c: virtual kernel memory mappings for high memory
   3 *
   4 * PowerPC version, stolen from the i386 version.
   5 *
   6 * Used in CONFIG_HIGHMEM systems for memory pages which
   7 * are not addressable by direct kernel virtual addresses.
   8 *
   9 * Copyright (C) 1999 Gerhard Wichert, Siemens AG
  10 *                    Gerhard.Wichert@pdb.siemens.de
  11 *
  12 *
  13 * Redesigned the x86 32-bit VM architecture to deal with
  14 * up to 16 Terrabyte physical memory. With current x86 CPUs
  15 * we now support up to 64 Gigabytes physical RAM.
  16 *
  17 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
  18 *
  19 * Reworked for PowerPC by various contributors. Moved from
  20 * highmem.h by Benjamin Herrenschmidt (c) 2009 IBM Corp.
  21 */
  22
  23#include <linux/export.h>
  24#include <linux/highmem.h>
  25
  26/*
  27 * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
  28 * gives a more generic (and caching) interface. But kmap_atomic can
  29 * be used in IRQ contexts, so in some (very limited) cases we need
  30 * it.
  31 */
  32#include <asm/tlbflush.h>
  33
  34void *kmap_atomic_prot(struct page *page, pgprot_t prot)
  35{
  36
  37        unsigned long vaddr;
  38        int idx, type;
  39
  40        preempt_disable();
  41        pagefault_disable();
  42        if (!PageHighMem(page))
  43                return page_address(page);
  44
  45
  46        type = kmap_atomic_idx_push();
  47        idx = type + KM_TYPE_NR*smp_processor_id();
  48        vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  49#ifdef CONFIG_DEBUG_HIGHMEM
  50        BUG_ON(!pte_none(*(kmap_pte-idx)));
  51#endif
  52        set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot));
  53        local_flush_tlb_page(NULL, vaddr);
  54
  55        return (void *) vaddr;
  56}
  57EXPORT_SYMBOL(kmap_atomic_prot);
  58
  59void __kunmap_atomic(void *kvaddr)
  60{
  61        unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  62        int type;
  63        unsigned int idx;
  64
  65        if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
  66                pagefault_enable();
  67                preempt_enable();
  68                return;
  69        }
  70
  71        type = kmap_atomic_idx();
  72
  73        idx = type + KM_TYPE_NR * smp_processor_id();
  74#ifdef CONFIG_DEBUG_HIGHMEM
  75        BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
  76#endif
  77        /*
  78         * force other mappings to Oops if they'll try to access
  79         * this pte without first remap it
  80         */
  81        pte_clear(&init_mm, vaddr, kmap_pte-idx);
  82        local_flush_tlb_page(NULL, vaddr);
  83
  84        kmap_atomic_idx_pop();
  85        pagefault_enable();
  86        preempt_enable();
  87}
  88EXPORT_SYMBOL(__kunmap_atomic);
  89